Making eye contact and small chat implies a connection. I know this because on calls at work we are required to do small talk to "create rapport" and a sense of intimacy.
I am not sure why anyone would want this with a stranger and it seems to only apply when you are the help and doing customer service... because in public... you sure as heck do NOT want random intimacy. It's creepy. And culturally, it's far worse coming from a male as intimacy implies sex and sex with strange males is rather frowned upon in America.
What happened to the small town feel? It was eaten alive by "stranger danger" and xenophobia. Sure, once upon a time in America, one wanted to know their neighbors and anyone new was intently interviewed by half the town. Times, however, have changed. Now only small children and the mentally ill give friendly hellos to strangers. The rest of us have been taught that this is dangerous and foolish.
Personally, I think the isolation is far more dangerous. Parents are too scared to let their kids play outside and explore, seriously inhibiting their physical health and mental growth. I'm sure the current "lack of vitamin D" epidemic is influenced by that fear: kids are kept "safely" indoors. When I was growing up, we ran around outside all the time. Met strange children from other neighborhoods. Went exploring. Had neighborhood barbeques. Watched neighbors' pets when they were out of town and shoveled elderly neighbors snowy driveways just because.
A lot of that is missing today and I think most people are diminished by the lack of neighbors. They seem to have fewer really close friends as well. But we are social animals and the lack of social contact takes its toll. Babies die of failure to thrive from lack of touch. Adults just get depressed and mental agility. It even influences heart conditions!
This fear of social intimacy seems to be growing. Personally, I think having the good excuses of aspergers and other spectrum disorders just makes it worse. Now you have an excuse to not put an effort into expanding your social circle. How is that helpful? With diagnoses of social phobia and anxiety disorders just gives permission to hide away. We create more sickness by approving the fears. Yes, yes. Meeting people is terrifying. Eventually, you have to realize if everything scares you, the fear ceases to count.
Then again, I think people greatly enjoy being sick and so it's probably an added benefit to those sorts that their "disorders" add to their physical distress. It's like a badge of honour to be ill. If you don't have enough diagnoses you have something wrong with you?
The real question is, how does one break out of the loop by being friendly to neighbors without getting a restraining order slapped on them by a sociophobe or well meaning but over protective parent?